Comment by wizofaus

Almost certain that all animals have it? The conjecture that, say, a coral polyp or an earthworm (not to mention something like a trichoplax) might have a subjective qualitative experience of existence seems to be an extraordinary claim requiring extraordinary proof. I don't know exactly how similar a brain has to be to a human brain for us to say with reasonable confidence the owner likely has such an experience but I'd be very surprised if included even half of all known animal species. It's possibly not even all (adult) mammals, and indeed not even all humans if you include infants and possibly those with severe brain damage etc.